Rotor of a built-in motor

ABSTRACT

A rotor of a built-in motor includes a shaft having a stepped part and a sleeve having a hollow space arranged to cover the stepped part of the shaft and a hydraulic pressure supply means. The sleeve is fitted with the shaft at the stepped part. A core is fitted with the sleeve. Hydraulic pressure applied to the hollow space within the sleeve via the hydraulic pressure supply means loosens the fit between the sleeve and the shaft, thereby allowing the shaft to be readily removed from the sleeve and core portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a rotor of a built-in motor. Morespecifically, this invention relates to an improvement applicable to thestructure of a rotor of a built-in motor, for the purpose of enablingthe shaft of the built-in motor to be readily removed from the core ofthe built-in motor.

2. Description of the Related Art

It is not necessarily difficult to fit the shaft of an electric motorwith the core of the electric motor, because various convenient methods,such as force fit, shrinkage fit, etc., are available. It is notnecessarily easy, however, to remove the shaft of an electric motor fromthe core of the electric motor, because application of a considerablemagnitude of heat, pressure or the like is generally required for thispurpose.

Since a built-in motor has a stator which is mounted, with a flange, ona machine which is driven by the built-in motor, and since it has arotor which is fitted with the shaft of the machine which is driven bythe built-in motor, the core is inclined to be frequently required to beremoved from the shaft.

Therefore, a structure which allows a shaft to be readily removed from acore is desirable for a built-in motor.

SUMMARY OF THE INVENTION

The object of this invention is to provide a rotor of a built-in motorhaving a structure which allows the shaft to be readily removed from thecore part thereof, whenever it is required.

To achieve the above mentioned object, a rotor of a built-in motor inaccordance with this invention is provided:

a shaft (1) having a stepped part (11);

a sleeve (2) having a hollow space (21) arranged to cover the steppedpart (11) and a hydraulic pressure supply means (22) and being fittedwith the shaft (1) having the stepped part (11); and

a core (3) being fitted with the sleeve (2).

In other words, a rotor of a built-in motor in accordance with thisinvention has a core (3) which is fitted with a sleeve (2) which isfurther fitted with a shaft (1), remaining a hollow space (21) thereinat a location to cover a stepped part (11) of the shaft (1). The sleeve(2) has a hydraulic pressure supply means (22) for supplying hydraulicpressure into the hollow space (21) which is asymmetrical from side toside (or which has one end (23) whose area is larger than that of theother end (24)). Therefore,the core (3) and sleeve (2) can readily beremoved from the shaft (1) by applying hydraulic pressure to the hollowspace (21) employing the above mentioned hydraulic pressure supply means(22), because it exerts a thrust in the direction of the shaft (1) basedon the above mentioned asymmetry of the above mentioned sleeve (2) (orbased on the difference in area of the one end (23) and the other end(24) of the above mentioned sleeve (2)).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing the assembled position of therotor of a built-in motor of one embodiment of this invention; and

FIG. 2 is a cross-sectional view showing the rotor of a built-in motorof the embodiment of FIG. 1 being disassembled in which the sleevecarrying the core is removed from the shaft.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1, a shaft 1 (which is usually the shaft of a machinedriven by the built-in motor, not shown in the drawings) has a steppedpart 11. A sleeve 2 has a hollow space 21 therein. The one end 23 of thesleeve 2 is fitted with the shaft 1 on the right side of the steppedpart 11 as shown in the drawing (or the one end 23 of the sleeve 2 isfitted with the shaft 1 at a location at which the diameter of the shaft1 is smaller), and the other end 24 of the sleeve 2 is fitted with theshaft on the left side of the stepped part 11 as shown in the drawing(or the one end 24 of the sleeve 2 is fitted with the shaft 1 at alocation at which the diameter of the shaft 1 is larger). As a result,the sleeve 2 is asymmetrical from side to side. The sleeve 2 has ahydraulic pressure supply means 22 for supplying hydraulic pressure intothe hollow space 21 of the sleeve 2.

A rotor core 3 having a set of windings 4 is permanently fitted on thesleeve 2. In other words, there is little chance for the core 3 to beremoved from the sleeve 2.

When this rotor is assembled, the core 3 is fitted with the sleeve 2.Then, the sleeve 2 is heated, before it is pushed to the left and iffitted with the shaft 1 with the shrinkage fit, as shown in the drawing.

Referring to FIG. 2, when this rotor is disassembled (or when the sleeve2 is removed from the shaft 1), hydraulic pressure with a high pressureof approximately 700 Kg/cm² is applied into the hollow space 21,employing the hydraulic pressure supply means 22.

An application of this magnitude of hydraulic pressure causes the sleeve2 to be elastically deformed, and the friction beteween the both ends 23and 24 of the sleeve 2 and the shaft 1 is decreased due to a decrease inthe pressure between the sleeve 2 and the shaft 1. As a result, even alittle difference in the area existing between the both ends 23 and 24of the sleeve 2, readily causes the sleeve 2 to be shifted in thedirection of an arrow shown in the drawing (in the direction from theend whose area is smaller to the end whose area is larger) andresultantly to be removed from the shaft 1. In this way, the core 3 canreadily be removed from the shaft 1.

The foregoing description has clarified that this invention hassuccessfully provided a rotor of a built-in motor having a structurewhich allows the shaft to be readily removed from the core thereof,wheneven it is required.

Although the foregoing description was presented referring to a specificembodiment, this is not meant to be construed in a limiting sense.Various modifications of the disclosed embodiment, as well as otherembodiments of this invention, will be apparent to persons skilled inthe art upon reference to the description of this invention. It istherefore contemplated that the appended claims will cover any suchmodifications or embodiments as fall within the true scope of thisinvention.

We claim:
 1. A rotor of a built-in motor comprising:a shaft having astepped part ; a sleeve havinga hollow space arranged to surround saidshaft at said stepped part, and a hydraulic pressure supply means forapplying hydraulic pressure to said sleeve, reducing friction betweensaid shaft and said sleeve and removing said sleeve from said shaft,said sleeve being fitted with said shaft having the stepped part; and acore fitted with said sleeve.
 2. A motor built into a machine fordriving the machine, comprising:a shaft having a step between arelatively large diameter portion and a relatively small diameterportion thereof, said shaft being integral with the machine; a hollowasymmetrical sleeve fitted about said shaft at the step; hydraulicpressure supply means for supplying hydraulic pressure to said hollowsleeve to elastically deform said sleeve, reduce friction between saidshaft and said sleeve and shift said sleeve away from the large diameterportion of said shaft in the direction of the small diameter portion sothat said sleeve and said sleeve can be separated from said shaft; and arotor core for driving said shaft fitted with said sleeve and separablefrom said shaft.
 3. A motor according to claim 2, wherein said hollowasymmetrical sleeve is shrink fitted onto said shaft.
 4. A motoraccording to claim 2, wherein said motor core further includes windings.5. A motor according to claim 2, wherein said sleeve has a first endfitted with the large diameter portion of said shaft and a second endfitted with the small diameter portion of said shaft.
 6. A motor builtinto a machine for driving the machine, comprising:a shaft having a stepintegral with the machine for driving the machine, said shaft having afirst portion with a first diameter on a first side of the step and asecond portion having a second diameter, smaller than said firstdiameter, on a second side of the step; a hollow sleeve fitted aboutsaid shaft having a first end fitted with the first portion of saidshaft and a second end fitted with the second portion of said shaft;hydraulic pressure supply means for supplying hydraulic pressure to saidhollow sleeve to elastically deform said sleeve, reduce friction betweensaid shaft and said sleeve and shift said sleeve away from the largediameter portion of said shaft and in the direction of the smalldiameter portion, so that said sleeve can be separated from said shaft;and a rotor core fitted with said sleeve and separable from said shaft,for driving said shaft.
 7. A motor according to claim 6, wherein saidsleeve is shrink fitted about said shaft.
 8. A motor according to claim6, wherein said removable separable rotor core further includeswindings.
 9. A motor according to claim 6, wherein the first end of saidsleeve has a first area and the second end of said sleeve has a secondarea, the second area being larger than the first area.